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The Daily Vet is a blog featuring veterinarians from all walks of life. Every week they will tackle entertaining, interesting, and sometimes difficult topics in the world of animal medicine – all in the hopes that their unique insights and personal experiences will help you to understand your pets.

Vaccinations are a necessity for keeping your cat healthy, particularly as a kitten. But which vaccines and when should they be given?

Let’s start at the beginning. A vaccination, which is sometimes also referred to as an immunization, is a medication which stimulates an immune response in your pet to provide protection against a particular disease, or group of diseases.

Vaccinations are divided into two groups: the core vaccines and the non-core vaccines. Core vaccines are recommended for all cats either because the disease the vaccine protects against is extremely severe and/or is especially common, or the disease is a threat to humans. Non-core vaccines are recommended only for those cats whose life-styles or living situations place them at risk for the disease in question.

Feline calicivirus and feline rhinotracheitis are the two viruses most commonly responsible for upper respiratory infections in cats. They are common viruses and almost all cats will be exposed to them at some point in their life.

Feline panleukopenia is a parvovirus that can prove to be fatal for infected cats, especially young cats. The disease is often called feline distemper, although this name is, in fact, a bit of a misnomer.

Rabies is a fatal disease that is contagious not only to other animals but to people as well.

Kittens should be started on vaccinations as early as six weeks of age. Vaccines are available that protect against feline panleukopenia, feline calicivirus, and feline rhinotracheitis all in one vaccination. This vaccination should be repeated at 3-4 week intervals until your kitten is at least 16 weeks of age and then repeated one year later.

Rabies vaccines, depending on the type of vaccine your veterinarian uses, can be given either at 8 weeks or at 12 weeks of age. This vaccine should be repeated in one year.

For adult cats, you’ll need to consult with your veterinarian concerning the proper vaccination interval. In some instances and depending on which vaccine brand is being used, vaccinations may need to be given at one year intervals. For instance, some rabies vaccines must be repeated yearly. In other cases, revaccination every three years may be recommended.

Non-core vaccinations for cats include vaccinations for diseases such as:

The need for these vaccinations is determined on a case by case basis. In the case of the feline leukemia vaccine, only those adult cats at risk of infection should be routinely vaccinated, although many veterinarians (but not all) believe that all kittens should be vaccinated against feline leukemia.

Some veterinarians recommend the feline AIDS vaccine for cats that are at risk while others believe that the risk of the vaccine does not outweigh the risk of the disease. Your veterinarian can advise you about the risks of the vaccine for your cat and help you make an appropriate decision.

The vaccine for feline infectious peritonitis is not generally recommended for most cats. Only under very specific circumstances would this vaccination be recommended for your cat.

Vaccinations against Chlamydophila felis and Bordetella bronchiseptica are not routinely administered to most cats either. They may be considered if your cat is required to enter an environment in which these bacteria are causing disease.

That's a valid concern. Where there is doubt, vaccinations can be given individually at 3-4 week intervals to avoid overwhelming the immune system. For instance, the feline calicivirus/rhinotracheitis/panleuk vaccine could be given in one visit with the rabies vaccine administered in 3-4 weeks if necessary. In many instances, that won't be necessary but it is an option to consider.

The veterinary profession realizes that vaccines are not harmless. This is the reason that vaccines are divided into core and non-core vaccines. It is also the reason that vaccination intervals are different now than they were years ago.

Over the years, our understanding of the immune system and the effects of vaccines on the immune system has grown and we have modified our vaccination protocols as a result. However, especially in the case of kittens, avoiding vaccinations altogether because of the risks is just as dangerous if not moreso than properly protecting them through vaccination.

Speaking from the perspective of someone who has watched kittens die of panleukopenia, it's not something I care to see again, especially when I know I can prevent it.

It's also worth noting that in some communities, if your pet is unvaccinated and exposed to rabies, it must either be quarantined for as long as six months or euthanized. (Some communities will allow measuring titers for rabies in lieu of vaccination. In those communities, this is another option for pet owners.)

I am a petsitter with a number of clients' cats which are not vaccinated because they are indoor only and my clients believe they are therefore not at risk. Could you elaborate more on how a cat could be at risk for contracting the diseases listed above? I am assuming some of them could actually be brought into the home by humans. For example, I visit a lot of other pets throughout the day, and also volunteer at shelters. Couldn't I, then, be exposing their cats to diseases? Thanks!

Yes, you're absolutely right. You could indeed bring an upper respiratory virus (for instance) into your client's home on your clothing or skin, as could anyone else entering their home. That being said, these viral infections do tend to be more common and more severe in kittens and young cats. Older cats often have developed some innate immunity.

In regards to viruses such as feline leukemia or feline AIDS, these viruses are unlikely to be carried on skin and clothing.

Rabies vaccines are required by law in many communities regardless of whether cats live indoors or out. There have been instances of wild animals and bats sneaking into a home and potentially exposing a pet cat to rabies. In addition, nobody wants to believe that their indoor-only cat will ever escape but accidents do happen. Cats that unvaccinated and exposed to rabies are subject to quarantine for long periods (usually six months) or to euthanasia because of the threat to people.

I find it odd that you would write a column on cat vaccinations and fail to mention safe vaccination sites (as low on the leg as possible) and Vaccine Associated Sarcoma. It's not nearly as rare as some say...I would say it is underdiagnosed because most pet owners won't spend thousands of dollars to attempt to treat this deadly cancer. My cat, Chicken, developed VAS in November 2010 and it was terrible. You can read about her fight here: http://chickenthecat.wordpress.com